Solid-state imaging devices, which are used widely for video cameras and still cameras or the like, are provided in the form of a package, in which an imaging element, such as a CCD or the like, is mounted on a base made of an insulating material, with the photo detecting region being covered by a transparent plate. In order to make the device more compact, the imaging element is mounted on the base as a bare chip. FIG. 6 shows the solid-state imaging device disclosed in JP H5-267629A, which is a conventional example of such a solid-state imaging device.
In FIG. 6, numeral 21 denotes a base, on the upper surface of which a recessed portion is formed, and in the center of the recessed portion an imaging element chip 22 is fixed. Lead terminals 24 are provided on the base 21, and lead pads 25 and bonding pads 23 of the imaging element chip 22 are connected by bonding wires 26 made of metal. Furthermore, ribs 28 are provided on an upper surface of the outer peripheral portion of the base 21, with a transparent sealing glass plate 27 fixed to the upper portion thereof, thus forming the package for protection of the imaging element chip 22.
Such a solid state imaging device is mounted on a circuit board with the sealing glass plate 27 facing upward, as shown in the figure, and the lead terminals 24 are used to connect it to the electrodes on the circuit board. Although not illustrated, a lens barrel incorporating an imaging optical system is mounted on top of the sealing glass plate 27 so that the relative positioning with respect to the photo detecting region formed in the imaging element chip 22 is adjusted with a predetermined precision. During the imaging operation, object light that has passed through the imaging optical system incorporated in the lens barrel is focused on the photo detecting region and photoelectrically converted.
In the conventional example of the solid-state imaging device described above, the sealing glass plate 27 is fixed with an adhesive to the upper surface of the ribs 28. Consequently, it is difficult to avoid the protrusion of some adhesive onto the inside face of the sealing glass plate 27 on the inner side of the ribs 28. Thus, there is the possibility of detrimental effects on the light that is incident on the photo detecting region of the imaging element chip 22, because the protruding adhesive blocks or scatters the incident light.
Furthermore, in the manufacturing step of the conventional solid-state imaging device, since the ribs 28 are formed in one piece with the base 21, it is inevitable that the sealing glass plate 27 is fixed by the adhesive to the upper surface of the ribs 28. Thus, as described above, it is difficult to avoid the effect of adhesive protrusion.